Room temperature nematic liquid crystals

ABSTRACT

THE PRESENT INVENTION INVOLVES FORMULATION OF ROOM TEMPERATURE NEMATIC LIQUID CRYSTALS INVOLVING COMPOUNDS WHICH ARE SOLID AT ROOM TEMPERATURE, BUT WHEN DISSOLVED IN CERTAIN SOLVENTS BECOME TRUE LIQUID CYRSTALS.

3,826,757 ROOM TEMPERATURE NEMATIC LIQUID CRYSTALS Shi-Yin Wong, SantaMonica, Calif., assignor to Hughes 3,826,757 Patented July 30, 1974phenyl-p-methyl benzoate. These solvents exhibit no nematic mesophase atroom temperature by themselves,

but when certain solid nematic liquid crystals are dis solved therein,they become effective room temperature nematic liquid crystals.

Aircraft Comp ny, Culver y, Calif- 5 The Solid c pounds used In thepresent invention N0 Drawing. Flltigtsg ihglgzgkser. No. 290,197correspond to the formula 12 Claims US. Cl. 252-408 (I) ABSTRACT OF THEDISCLOSURE wherein The present invention involves formulation of room 0temperature nematic liquid crystals involving compounds X: oH:N or gwhich are solid at room temperature, but when dissolved R d h 1k incertain solvents become true liquid crystals. 15 zi omy are eac a Yhavlng from 1 t0 about 10 carbon O 0 BACKGROUND OF THE INVENTION YBOILO, or There has been an increasing search for elfective room andtemperature nematic liquid crystals. French Pat. No. 0 1,537,000 hasreported nematic liquid crystals for use 1 O o g l! in the dynamicscattering mode (DSM). Of the mixtures z 5 reported therein, only oneexhibits solid-mesophase tran- Or a direct bond. sition at roomtemperature, but the DSM effect is above The method for making thesecompounds has been room temp ratu cported in Vogel, Practical OrganicChemistry, Longmans DETAILED DISCLOSURE OF THE PRESENT 5 INVENTION Inpreparing the solutlons of the present invention, the compound ofFormula I is dissolved in one of the The present invention is concernedwith formulations named solvents in order to form a solution.Preferably, which show DSM at room temperature. The compositions thecomposition will contain 20 to 50 percent, by weight, are also useful inultraviolet-activated cells. The comof the solvent. The compounds ofFormula I may be used pounds used herein are solid at room temperature,but individually, or mixtures of them may be employed.-They can bedissolved in certain solvents to produce solutions dissolve readily withstirring in the solvent. Specific exwhich are true room temperaturenematic liquid crystals. amples of compounds which are useful within thescope The solvents useful in the present invention are: of the presentinvention are set out in Table 1 and are p-methylbenzylidene-p-n-butylaniline and p-n-butylnumbered 3 through 22, respectively.

TABLE 1 i 0 I! onxomnoQ-onmrQo-o-om o (Lo-Q0 our) on,

i QO-OwHmGH Table 2 sets forth 19 specific formulations made within thescope of the present invention. Compounds 1 and 2 arep-methylbenzylidene-p-n-butyl aniline and p'-n-butylphenyl-p-methylbenzoate, respectively.

TABLE 2C0ntinued While the solvent is non-mesomorphic at roomtemperature, the resulting solution with the nematic compounds ismesomorphic. In addition, a different scattering efiiciency can beobtained from these formulations by varying the composition. Forinstance, the scattering effect of a solution of compound 11 inp-methylbenzilidene-p-n-butyl aniline will be different at 40 percentsolution as compared to 50 percent solution. This difference is due tothe number of scattering centers created by the interaction of theliquid crystal compounds and the solvent.

In addition, the compositions have wider and lower temperatures ofnematic mesophase than prior art compositions. For example, composition1 in Table 2 has a mesophase between 20 to 51 C. The lowestsolidmesophase transition previously recorded was 10 C. This is thefirst time that the art has been presented with a room temperatureguest-host alignment liquid crystal.

The formulations can be used in dynamic scattering mode betweentransparent electrodes for display system, as described by Heilmeyer, etal., Proc. IEEE 56 1162 (1968). In addition, they are use in light cellsfor ultraviolet photoactivated dynamic scattering mode as set forth inReversible Ultraviolet Imaging with Liquid Crystals, by J. D. Margerum,J. Nimoy, and S.-Y. Wong, Applied Physics Letter, vol. 17, No. 2, pages5153, 1970.

I claim:

1. A liquid crystal solution consisting essentially of from 50-80% of acompound corresponding to the formula R and R are each alkyl having from1 to about 10 carbon atoms; Y is O,

or a direct bond; dissolved in p'-n-butyl phenyl-pmethyl benzoate. 2. Aliquid crystal solution consisting essentially of a compoundcorresponding to the formula wherein R and R are each alkyl having from1 to about 10 carbon atoms; Y is 0,

II 1 -0, or 0- 0 Z is O,

H 0-0, 0 Jo, or a direct bond; dissolved in p'-n-butyl phenyl-pmethylbenzoate. 3. A liquid crystal solution consisting essentially of from50-80% of a compound or a mixture of compounds corresponding to theformula wherein R and R' are each alkyl having from 1 to about 10 carbonatoms;

on a direct bond, dissolved in p-n-butyl phenyl-pmethyl benzoate. 4. Asolution of claim 2 wherein Y is O, and Z is 5. A solution of claim 2wherein Y is O and Z is a direct bond.

6 6. A solution of claim 2 wherein Y is and Z is O.

'7. A solution of claim 2 wherein Y and Z are each 0. 8. A solution ofclaim 2 wherein Y is o 0-i'30 10 and Z is 1r 9. A solution of claim 2wherein Y is O, and Z is o-d-o.

10. A solution of claim 2 wherein Y is o o-ii-o and Z is O. 11. Asolution of claim 3 wherein Y-is 0-ii-o and Z is O. 12. A solution ofclaim 3 wherein Y is O and Z is o o-ii-o.

References Cited UNITED STATES PATENTS 3,675,987 7/1972 Rafuse 252-408LC FOREIGN PATENTS 2,017,727 4/1970 Germany 252408 LC OTHER REFERENCESGlen H. Brown, Analytical Chemistry, vol. 41, N0. 13, November 1969, p.28A.

RALPH S. KENDALL, Primary Examiner JACQUELINE WARE, Assistant ExaminerUS. 01. X.R. 23 23o LC; 350 LC

